lttng-context-vuid.c

   1 /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
   2  *
   3  * lttng-context-vuid.c
   4  *
   5  * LTTng namespaced real user ID context.
   6  *
   7  * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   8  *               2019 Michael Jeanson <mjeanson@efficios.com>
   9  *
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/sched.h>
  14 #include <lttng/lttng-events.h>
  15 #include <lttng/lttng-tracer.h>
  16 #include <ringbuffer/frontend_types.h>
  17 #include <wrapper/user_namespace.h>
  18
  19 static
  20 size_t vuid_get_size(size_t offset)
  21 {
  22         size_t size = 0;
  23
  24         size += lib_ring_buffer_align(offset, lttng_alignof(uid_t));
  25         size += sizeof(uid_t);
  26         return size;
  27 }
  28
  29 static
  30 void vuid_record(struct lttng_ctx_field *field,
  31                  struct lib_ring_buffer_ctx *ctx,
  32                  struct lttng_channel *chan)
  33 {
  34         uid_t vuid;
  35
  36         vuid = lttng_current_vuid();
  37         lib_ring_buffer_align_ctx(ctx, lttng_alignof(vuid));
  38         chan->ops->event_write(ctx, &vuid, sizeof(vuid));
  39 }
  40
  41 static
  42 void vuid_get_value(struct lttng_ctx_field *field,
  43                 struct lttng_probe_ctx *lttng_probe_ctx,
  44                 union lttng_ctx_value *value)
  45 {
  46         value->s64 = lttng_current_vuid();
  47 }
  48
  49 int lttng_add_vuid_to_ctx(struct lttng_ctx **ctx)
  50 {
  51         struct lttng_ctx_field *field;
  52
  53         field = lttng_append_context(ctx);
  54         if (!field)
  55                 return -ENOMEM;
  56         if (lttng_find_context(*ctx, "vuid")) {
  57                 lttng_remove_context_field(ctx, field);
  58                 return -EEXIST;
  59         }
  60         field->event_field.name = "vuid";
  61         field->event_field.type.atype = atype_integer;
  62         field->event_field.type.u.integer.size = sizeof(uid_t) * CHAR_BIT;
  63         field->event_field.type.u.integer.alignment = lttng_alignof(uid_t) * CHAR_BIT;
  64         field->event_field.type.u.integer.signedness = lttng_is_signed_type(uid_t);
  65         field->event_field.type.u.integer.reverse_byte_order = 0;
  66         field->event_field.type.u.integer.base = 10;
  67         field->event_field.type.u.integer.encoding = lttng_encode_none;
  68         field->get_size = vuid_get_size;
  69         field->record = vuid_record;
  70         field->get_value = vuid_get_value;
  71         lttng_context_update(*ctx);
  72         return 0;
  73 }
  74 EXPORT_SYMBOL_GPL(lttng_add_vuid_to_ctx);